[time-nuts] GPSDO won't lock: OCXO aged out?

[Scott Newell]

At 09:01 PM 1/11/2021, paul swed wrote:
>Can you see what the xtal unit actually is.

Trimble "73090".


>I suspect there is not a hole to a trimmer cap. But potentially if you can

I peeled the sticker from the top--no holes hidden there or on the four sides.


>open it you could get to a cap or at least see the xtal and what caps are
>around it.

The can is partly soldered--not a full seam around the lid. It might 
be possible to open it up without too much damage. (Looks easier that 
the MV89 I opened years ago.)


>Other more difficult approach is to insert a purposeful offset. Maybe 6 V
>very current limited. Opamp would be the best way to do that. Just to see
>if you can pull it to 10 MHz.
>But it would also mean you have traced the efc control pin to some extent.

The EFC trace on the GPSDO board is accessible and wouldn't be hard 
to cut. EFC swings it about 8 Hz right now, but I'd need another 4 Hz 
or so. Not sure 50% is doable.


-- 
newell  N5TNL